Many services are today provided using broadband access over a broadband access node in a broadband access network. Particularly provisioning broadband services based on IP/Ethernet multicast technology is of importance for the network architecture of service providers. For example an application for distribution of TV signals (IPTV) but also other applications such as distribution of radio (radio channels) and business information can benefit from the multicast distribution technology. Irrespectively of which broadband access network that is used, bottlenecks will be produced which limits the amount of multicast traffic in a network. Such bottlenecks can be produced at any locations, among others bottlenecks may easily be produced on links which have a limited available transmission bandwidth and in network nodes which for example only have a limited memory capacity allocated for handling multicast channels as well as limited multicast performance capability. Bottlenecks can also influence unicast traffic for example in networks carrying multicast as well as unicast traffic but also in networks only carrying unicast traffic. This means that broadband access networks have to be provided with a mechanisms aiming at ensuring a proper delivery and QoS of a subscribed service, particularly a multicast service, but also a unicast service.
As an example, if it is attempted to receive three TV channels each using for example 10 Mbps over a DSL (Digital Subscriber Line) with a capacity of 20 Mbps, the quality of the three data streams corresponding to the three TV channels will be impaired. In the following reference will mainly be made to multicast traffic since for such traffic the problems are more pronounced than for unicast traffic, even if they also are present for unicast traffic.
In order to provide a required QoS for multicast traffic, today normally the number of multicast channels per end user are limited. This is for example discussed in DLS Forum TR-101: “Migration to Ethernet-based DSL Aggregation”, April 2006. However, different types of multicast channels require different amounts of transmission bandwidth. A HDTV channel typically requires 10 Mbps, whereas radio channels easily can be conveyed using only 64 kbps. The multicast resource admission control (RAC) as implemented today only provides a very coarse mechanism which does not take into account the properties of any individual multicast streams. An end user may be configured to receive only two multicast streams and there are no means to distinguish between a 10 Mbps HDTV channel and a 32 kbps radio channel, which will result in channels and resources being dropped unnecessarily. Furthermore, with today used techniques, to prevent bottlenecks, the utilization of network resources may, under certain circumstances be poor and there is no flexibility in allowing access to resources or services.